Effects of Moderate-to-Heavy Sled Training Using Different Magnitudes of Velocity Loss in Professional Soccer Players

Jump Squat Vs. Resisted Sprint Training Programs Applied to Elite Youth Soccer Players: Effects on Sprint and Power-Related Performance

ABSTRACT

Loturco, I, Pereira, LA, Mercer, VP, Oliveira, LP, Zanetti, V, Lima, L, Bastos, T, Moura, TBMA, and McGuigan, MR. Jump squat vs. resisted sprint training programs applied to elite youth soccer players: effects on sprint and power-related performance. J Strength Cond Res XX(X): 000-000, 2024-This study examined the effectiveness of 2 different and widely used training programs on the sprint and power-related performance of youth soccer players. Two distinct training strategies-vertically oriented jump squats (JSs) or horizontally oriented resisted sprints (RSs)-were executed under the same absolute loading conditions (i.e., 30% of the athletes' body mass [BM]) during a 4-week preseason period. Training schemes, loading intensities (based on %BM), and the number of experimental sessions were designed in conjunction with the soccer club's coaching staff, considering the calendar, available resources, and regular training programs. Twenty-five under-17 soccer players performed a series of speed, power, and jump tests before and after 10 resisted training sessions, consisting solely of loaded JS or RS. Overall, neither group (i.e., JS or RS training groups) exhibited any improvement in linear sprint and change-of-direction (COD) speed. Conversely, vertical jumping ability and peak velocity in the loaded JS increased significantly only in the JS group, which may positively affect players' performance and training prescription during short soccer preseasons. Given the challenges in enhancing sprint speed among soccer players during preseasons (and even over the competitive season), coupled with the limited effectiveness of RS in improving sprinting, COD, and jumping capabilities within congested and short training phases (i.e., ≤4 weeks), the regular use of RS training methods during these phases may be highly questionable. Coaches should carefully consider these critical limitations and potential disadvantages when designing neuromuscular training programs for soccer players during the preparatory phases of the annual training season.

Does Resisted Sprint Training Improve the Sprint Performance of Field-Based Invasion Team Sport Players? A Systematic Review and Meta-analysis

BACKGROUND

Developing the sprint performance of field-based invasion team sport (FITS) players is considered an essential training goal for FITS coaching practitioners, and thus numerous training methods are employed to elicit improvements. Although interest in resisted sprint training (RST) has grown considerably in recent times, there remains a lack of clarity around its utility in FITS, particularly regarding the use and effectiveness of heavier RST loads.

OBJECTIVES

The aims of this review were to (1) compare RST to unresisted sprinting, (2) examine if RST can improve sprint performance and (3) investigate if external load and the method of load prescription influence the impact of RST in FITS players.

METHODS

The systematic review and meta-analysis were conducted in compliance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. The search strategy included terms for RST, RST modalities and FITS, and was applied to PubMed, SPORTDiscus, Web of Science and OpenGrey databases. Methodological quality and risk of bias associated with each study were assessed using the Physiotherapy Evidence Database scale (PEDro) and Cochrane Risk of Bias assessment tool respectively.

RESULTS

Twenty-one studies met the inclusion criteria for this review and were included in the final analysis. The primary between-group analysis revealed no differences between RST and unresisted sprinting for developing the early acceleration, late acceleration and maximum velocity sprint phases. Secondly, a within-group analysis found significant improvements for resisted sprint training in the early acceleration (standardised mean difference [SMD] - 0.80) and late acceleration (SMD - 0.28) sprint phases, with no change detected for the maximum velocity phase. Finally, significant moderate improvements were found for light (SMD - 0.69) and very heavy (SMD - 1.01) loads during early acceleration.

CONCLUSIONS

Resisted sprint training achieved similar improvements in sprint performance to those found for unresisted sprinting during the acceleration and maximum velocity sprint phases. Within-group findings show RST is an effective method for improving early acceleration and late acceleration performance of FITS players. Finally, a subgroup analysis supports the use of light and very heavy loads for increasing early acceleration performance, while also highlighting greater benefits associated with using the percentage velocity decrement loading method.

CLINICAL TRIAL REGISTRATION

Open Science Framework, https://osf.io/thms7/ .

Is isokinetic shoulder strength a determinant of serve ball velocity in tennis?

The tennis serve is closely related to the quality of the tennis match. However, the isokinetic parameters associated with the tennis serve are still unclear. The aim of this study was to investigate the relationships between ball velocity and isokinetic shoulder strength in tennis serve and to determine isokinetic strength parameters that can predict tennis serve velocity. A total of 13 elite male athletes (16.8 ± 1.5 years) voluntarily participated in the study. The athletes' shoulder internal-external rotation, extension-flexion and abduction-adduction strengths were measured with 5-5-15 repetitions at 60°/s, 180°/s, 240°/s angular velocities. Later, the athletes' 1st, 2nd, and average serve ball speeds were determined using a handheld radar gun. Significant correlations were found between ball speed and isokinetic tennis serve strength (r = 0.556-0.819; p < 0.05). The correlations between ball speed and isokinetic strength performance were higher at 180°/s and 240°/s angular velocities. Extension (240°/s; r = 0.819), flexion (180°/s; r = 0.755), abduction (240°/s; r = 0.733), adduction (240°/s; r = 0.684) and internal rotation (180°/s; r = 0.803) were highly correlated with ball velocity. These findings suggest that strength training to increase the ball speed of the tennis serve should be performed fast at high angular velocities and planning should focus on the strength of extension, flexion, abduction, adduction and internal rotation.

Neuromuscular Performance Changes in Elite Futsal Players Over a Competitive Season

ABSTRACT

Spyrou, K, Alcaraz, PE, Marín-Cascales, E, Herrero-Carrasco, R, Cohen, DD, and Freitas, TT. Neuromuscular performance changes in elite futsal players over a competitive season. J Strength Cond Res XX(X): 000-000, 2022-A professional futsal season imposes a great amount of physiological and mechanical stress on players. The main aim of this study was to examine the changes in neuromuscular performance qualities across the season. Ten professional male players performed a 10-m sprint, standing long jumps (SLJs), and countermovement jumps (CMJs) during the competitive season (i.e., every ∼5 weeks from September to January). A one-way repeated measures ANOVA with post hoc pairwise comparisons and effect sizes (ESs) were used to analyze potential differences among these assessments. A significant and large decline was found in concentric peak power (p = 0.040; ES = 1.24). A nonsignificant and moderate decrease was observed in sprint ability (p = 0.155; ES = 1.03), CMJ height (p = 0.175; ES = 1.00), and SLJ distance (p = 0.164; ES = 1.03). Regarding other CMJ kinetic variables, nonsignificant and moderate changes were found. In summary, considering the neuromuscular performance tests and variables assessed, only concentric peak power in CMJ decreased significantly across the season; however, nonsignificant decrements were observed in sprinting time, SLJ, CMJ height, and other kinetic metrics. CMJ variables during the jump-land cycle should be incorporated alongside more traditional measures (e.g., jump height) to monitor performance during the season.

Speed-Related Abilities Are Similarly Improved After Sled Training Under Different Magnitudes of Velocity Loss in Highly Trained Soccer Players

PURPOSE

We examined the effects of two 8-week resisted-sprint training programs under different magnitudes of velocity loss (VL) on the speed-related performance of highly trained soccer players.

METHODS

Twenty-one soccer players (age: 25.9 [5.4] y) were randomly assigned to 1 of 2 groups: (1) the "moderate-load group," players who trained with sled loads that induced 15%VL relative to unloaded sprint velocity (n = 11); and (2) the "heavy-load group," players who trained with sled loads that induced 40% VL relative to unloaded sprint velocity (n = 10). Linear sprint (10 m), curve sprint, change-of-direction speed, resisted-sprint performance at 15% VL and 40% VL, and vertical jumping ability were tested pretraining and posttraining. A 2-way repeated-measures analysis of variance was used to test for differences between groups. In addition, percentage changes were calculated for speed-related abilities and compared with their respective coefficients of variation to determine whether individual changes in performance were greater than the test variance (ie, "true change").

RESULTS

A main effect of time was detected for 10-m sprint, curve sprint, change-of-direction speed, and 15% VL and 40% VL resisted-sprint times, with significant decreases in sprint times (P = .003, P = .004, P = .05, P = .036, and P = .019, respectively). Jump variables did not change significantly over time. There were no group-by-time interactions for any tested variable (P > .05), but the "true change" analysis revealed meaningful individual changes in both groups.

CONCLUSIONS

Both moderate- and heavy-sled loading conditions may optimize the development of speed-related abilities in highly trained soccer players. Nevertheless, resisted-sprint training responses may differ meaningfully when assessed on an individual basis.

Effect of Vertical Jump and Sprint Training on Power and Speed Performance Transfer

The aim of this systematic review was to investigate the effect of specific sprint and vertical jump training interventions on transfer of speed-power parameters. The data search was carried out in three electronic databases (PubMed, SCOPUS, and SPORTDiscus), and 28 articles were selected (13 on vertical jump training and 15 on sprint training). We followed the PRISMA criteria for the construction of this systematic review and used the Physiotherapy Evidence Database (PEDro) scale to assess the quality of all studies. It included studies with a male population (athletes and nonathletes, n = 512) from 18 to 30 years old who performed a vertical jump or sprint training intervention. The effect size was calculated from the values of means and SDs pre- and posttraining intervention. The percentage changes and transfer of training effect were calculated for vertical jump training and sprint training through measures of vertical jump and sprint performance. The results indicated that both training interventions (vertical jump training and sprint training) induced improvements in vertical jump and linear sprint performance as well as transfer of training to speed-power performance. However, vertical jump training produced greater specific and training transfer effects on linear sprint than sprint training (untrained skill). It was concluded that vertical jump training and sprint training were effective in increasing specific actions of vertical jump and linear sprint performance, respectively; however, vertical jump training was shown to be a superior alternative due to the higher transfer rate.

Internal Validity in Resistance Training Research: A Systematic Review

Ensuring internal validity is the key procedure when planning the study design. Numerous systematic reviews have demonstrated that considerations for internal validity do not receive adequate attention in the primary research in sport sciences. Therefore, the purpose of this study was to review methodological procedures in current literature where the effects of resistance training on strength, speed, and endurance performance in athletes were analyzed. A computer-based literature searches of SPORTDiscus, Scopus, Medline, and Web of Science was conducted. The internal validity of individual studies was assessed using the PEDro scale. Peer-reviewed studies were accepted only if they met all the following eligibility criteria: (a) healthy male and female athletes between the ages of 18-65 years; (b) training program based on resistance exercises; (c) training program lasted for at least 4 weeks or 12 training sessions, with at least two sessions per week; (d) the study reported maximum strength, speed, or endurance outcomes; and (e) systematic reviews, cohort studies, case-control studies, cross-sectional studies were excluded. Of the 6,516 articles identified, 133 studies were selected for rating by the PEDro scale. Sixty-eight percent of the included studies used random allocation to groups, but only one reported concealed allocation. Baseline data are presented in almost 69% of the studies. Thirty-eight percent of studies demonstrated adequate follow-up of participants. The plan to follow the intention-to-treat or stating that all participants received training intervention or control conditions as allocated were reported in only 1.5% of studies. The procedure of blinding of assessors was also satisfied in only 1.5% of the studies. The current study highlights the gaps in designing and reporting research in the field of strength and conditioning. Randomization, blinding of assessors, reporting of attrition, and intention-to-treat analysis should be more fully addressed to reduce threats to internal validity in primary research.

Effect of velocity loss during squat training on neuromuscular performance

This study aimed to compare the effects of three resistance training (RT) programs differing in the magnitude of velocity loss (VL) allowed in each exercise set: 10%, 30%, or 45% on changes in strength, vertical jump, sprint performance, and EMG variables. Thirty-three young men were randomly assigned into three experimental groups (VL10%, VL30%, and VL45%; n = 11 each) that performed a velocity-based RT program for 8 weeks using only the full squat exercise (SQ). Training load (55-70% 1RM), frequency (2 sessions/week), number of sets (3), and inter-set recovery (4 min) were identical for all groups. Running sprint (20 m), countermovement jump (CMJ), 1RM, muscle endurance, and EMG during SQ were assessed pre- and post-training. All groups showed significant (VL10%: 6.4-58.6%; VL30%: 4.5-66.2%; VL45%: 1.8-52.1%; p < 0.05-0.001) improvements in muscle strength and muscle endurance. However, a significant group × time interaction (p < 0.05) was observed in CMJ, with VL10% showing greater increments (11.9%) than VL30% and VL45%. In addition, VL10% resulted in greater percent change in sprint performance than the other two groups (VL10%: -2.4%; VL30%: -1.8%; and VL45%: -0.5%). No significant changes in EMG variables were observed for any group. RT with loads of 55-70% 1RM characterized by a low-velocity loss (VL10%) provides a very effective and efficient training stimulus since it yields similar strength gains and greater improvements in sports-related neuromuscular performance (jump and sprint) compared to training with higher velocity losses (VL30%, VL45%). These findings indicate that the magnitude of VL reached in each exercise set considerably influences the observed training adaptations.